A federal courtroom was transformed into a rhythmic hip-hop battlefield Tuesday with jurors bobbing their heads in a copyright trial pitting a New Jersey group against rappers Ludacris and Kanye West.

Music group IOF claims Christopher "Ludacris" Bridges and Grammy award winner Kanye West breached copyright laws by stealing lyrics and style from the little-known group's song "Straight Like That," using it for their 2003 hit single "Stand Up."

The four members of IOF, standing for It's Only Family, say they distributed copies of their song to music executives in 2002 and 2003, only to later recognize elements of their song in Ludacris' "Stand Up," coproduced by West.

A lawyer for Ludacris and West clapped her hands and played a compilation of other songs to persuade the jury and observers that similar rhythms and the chorus words "like that"--contained in both songs--were not original to IOF.

"The first time they heard the song 'Straight Like That' was when this lawsuit was filed," said lawyer Christine Lepera, arguing for the two famed rappers and the other defendants: publisher EMI April Music Publishing, distributor Universal Music, Video Distribution Corporation, and Def Jam Music Group.

"There are scores of songs out there with the words 'like that' with that type of rhythm," Lepera said. "They do not need to copy anyone's music."

She played the entire hit song to the jury with the catchy chorus "When I move you move, just like that" while Ludacris joined jurors in bobbing his head.

But IOF lawyer Mel Sachs said there was "a constellation of similarities" between the two songs, including the main chorus lyrics as well as a "call and response" song style.

"This song 'Stand Up' catapulted Ludacris's career. ... It was certified gold by the recording industry" by selling more than 500,000 copies, Sachs said.

IOF "put a lot of time and effort into doing this song and then it was taken away from them," he said.

The trial is expected to last two weeks and will determine if there is liability before any monetary damages can be claimed. Though West was not in court on Tuesday, he is expected to testify at some point.